The present invention relates to a colored aromatic polycarbonate resin composition, a process for producing the same, and a colored hollow container. More particularly, the present invention relates to a colored aromatic polycarbonate resin composition which exhibits an excellent hue, and is improved in heat resistance and hydrolysis resistance, a process for producing the colored aromatic polycarbonate resin composition, and a colored hollow container using the colored aromatic polycarbonate resin composition.
Aromatic polycarbonate resins have been extensively used in various applications such as optical disks, OA apparatuses, medical parts and food containers because these resins are excellent in heat resistance, mechanical properties such as impact resistance and dimensional stability as well as transparency. In particular, in the application field of food containers, the aromatic polycarbonate resins are blended with a larger amount of pigments or dyes than that used ordinarily to form a colored container. Upon coloring these resins, if the colorants are poorly dispersed in the resins, the resultant container tends to suffer from unevenness of hue.
To enhance a dispersibility of the pigments or dyes in the aromatic polycarbonate resin, these components may be forcibly kneaded together using an extruder. However, in such a case, there tends to be caused such a problem that a part of the aromatic polycarbonate resin is colored due to thermal decomposition, and a molecular weight of the resin is decreased, thereby failing to attain an aimed melt viscosity thereof. In addition, the obtained aromatic polycarbonate resin composition tends to be deteriorated in heat resistance and hydrolysis resistance. In particular, in the case of blow-molded food containers, contour-molded products, twin-wall sheet molded products or multi-wall sheet molded products, aromatic polycarbonate resins used therefor are required to have a large molecular weight or contain a large amount of branched constitutional units, i.e., exhibit a high melt tension. Therefore, the above problems tend to become more remarkable when the aromatic polycarbonate resins are used in these molded products.
To solve these problems, there is known a method of producing a colored aromatic polycarbonate resin composition by adding a polyalkyleneglycol derivative represented by the general formula: R2COO—(CH2—CHR1—O)m—R3 (wherein R1 is a hydrogen atom or a lower alkyl group, R2 is an alkyl group having 1 to 30 carbon atoms or a phenyl group substituted with 0 to 2 lower alkyl groups, R3 is a hydrogen atom or an acyl group having 1 to 30 carbon atoms; and m is an integer of 1 to 1000), together with an anthraquinone-based dye, to an aromatic polycarbonate resin (Japanese Patent Application Laid-Open (KOKAI) No. 5-117516(1993)).
The above polyalkyleneglycol derivative exhibits a certain degree of color-development promoting effect when used together with the aromatic polycarbonate resin having a small molecular weight or containing a less amount of branched constitutional units. However, when used together with the aromatic polycarbonate resin having a large molecular weight or containing a large amount of branched constitutional units (i.e., aromatic polycarbonate resin having a high melt tension), the color-development promoting effect of the polyalkyleneglycol derivative is insufficient.